In Long Term Evolution (LTE), operations of Coordinated Multi-Point (CoMP) reception (hereinafter referred to as UL-CoMP) in the uplink have been studied (for example, see NPL 1). In CoMP reception, a plurality of base stations receive signals transmitted from one terminal, and synthesize the signals received in each base station to improve the reception quality of the signals.
In UL-CoMP, the received signals of each of the plurality of base stations which receive signals from the terminal in a coordinated way are forwarded to a base station performing synthesis/decoding processing. In the following description, among a plurality of base stations participating in UL-CoMP, a base station that performs synthesis/decoding processing is referred to as a “synthesizing base station” and a base station that forwards the received signals to the synthesizing base station is referred to as a “forwarding base station”.
FIG. 1 illustrates an example of an environment in which UL-CoMP may be applied. In FIG. 1, terminal A and terminal B are located in each end of coverage area (cell edge) of base station A and base station B, and connected to base station A and base station B respectively. In this case, with respect to uplink signals of terminal A, not only signal power is reduced due to the distance attenuation to base station A, but also interference caused by the uplink signals of terminal. B is generated, and thereby reception quality deteriorates. Similarly, reception quality deteriorates for the uplink signals of terminal B.
In contrast, in UL-CoMP, base station A and base station B receive uplink signals of each of terminal A and terminal B in a coordinated way and synthesize the signals received in each base station to improve reception quality of the signals.